The invention relates to the technical field of projectiles guided by incidence steerable control surfaces.
To guide a projectile up to its target, it is known to use control surfaces (or fins) arranged on the periphery of the projectile, either at the empennage or in front position (control surfaces known as foreplane or canard control surfaces). The incidence of the control surfaces is adapted while airborne according to the desired trajectory for the projectile. The incidence piloting is most often performed by electrical motors. The U.S. Pat. No. 7,246,539 discloses a piloting device of control surfaces of a projectile comprising four control surfaces as well as gear trains associated with motors enabling to set the incidence of the control surfaces.
This type of device requires to know the exact angular position, both for incidence and rolling, of each control surface to make the control surface adopt the suitable position to make the projectile follow the desired trajectory. The projectile undergoing a rolling which can be very important, particularly if it is fired from a rifled canon weapon, it is thus necessary to perform continuous corrections on the incidence of the control surfaces.
These corrections have to be performed extremely quickly, requiring fast calculating means and fast movements of the control surfaces. These fast movements generate current peaks in motors, causing a control in fits and starts of the motors. These current peaks are also the cause of intense and irregular magnetic fields in motors. These fields affect the projectile guiding means such as homing devices or other sensing devices. Furthermore, the solution suggested by U.S. Pat. No. 7,246,539 is complex in terms of number of gear trains and movement transmission parts.